Hashmat the brave warrior

hashmat.hs

#!/usr/bin/env runhaskell

-- Andrew Pennebaker
-- 21 April 2011

import Data.String.Utils (split)
import Data.List (intercalate)

-- Thanks to aavogt at #haskell
maybeRead :: Read a => String -> Maybe a
maybeRead s = case reads s of
	(r, ""):[] -> Just r
	_ -> Nothing

diff :: String -> String -> Int
diff sa sb = case (maybeRead sa, maybeRead sb) of
	(Just a, Just b) -> abs (a - b)
	_ -> 0

diffLine :: String -> String
diffLine input = unlines $ map diffLine' $ lines input
	where
		diffLine' :: String -> String
		diffLine' line = show $ case split " " line of
			a:b:_ -> diff a b
			_ -> 0

main :: IO ()
main = interact diffLine